1. Field of the Invention
The present invention relates to a monolithic ceramic electronic component, and more particularly to a monolithic ceramic electronic component provided with outer electrodes including plated films that are directly disposed on outer surfaces of a ceramic base element.
2. Description of the Related Art
Recently, sizes of electronic devices, such as cellular phones, notebook personal computers, digital cameras, and digital audio devices, have become increasingly smaller. Monolithic ceramic electronic components capable of being manufactured to have smaller sizes but with higher performance have been used in many of such electronic devices.
The monolithic ceramic electronic component usually includes a ceramic base element including a plurality of stacked ceramic layers, inner electrodes formed inside the ceramic base element, and outer electrodes formed on outer surfaces of the ceramic base element. Further, the monolithic ceramic electronic component is placed on conductive lands of a mounting board and is mounted to the board by using a conductive bonding material, e.g., a solder.
There are still now continuing demands for further size reduction of monolithic ceramic electronic components.
However, when the size of the monolithic ceramic electronic component is reduced, an effective area where the inner electrodes are opposed to each other is also reduced. Hence characteristics of the monolithic ceramic electronic component generally tend to degrade.
Further, in a multi-terminal monolithic ceramic electronic component, it is necessary to form a plurality of stripe-shaped outer electrodes at a narrow pitch. However, a known method of baking a thick film paste has a limit in accuracy of applying the paste and has a difficulty in forming the outer electrodes with high accuracy.
In view of such a situation, a method of forming the outer electrodes directly by plating is proposed. With that method, thin and flat outer electrodes can be formed, and hence the effective area of the inner electrodes can be increased. Moreover, because plated metals are deposited on the exposed portions of the inner electrodes, the outer electrodes can be formed with high accuracy even at a narrow pitch.
To realize more reliable growth of the plated metals when the outer electrodes are formed directly by plating, Japanese Unexamined Patent Application Publication No. 2004-327983, for example, proposes the use of dummy conductors (anchor tabs). According to the technique disclosed in Japanese Unexamined Patent Application Publication No. 2004-327983, plated metals can be deposited on not only the exposed portions of the inner electrodes, but also on the exposed portions of the dummy conductors. Therefore, growth of the plated metals can be more reliably ensured.
With the method disclosed in Japanese Unexamined Patent Application Publication No. 2004-327983, however, reliability, e.g., breakdown voltage or BDV, of the monolithic ceramic electronic component may degrade in some cases. The inventors of the invention described and claimed in the present application have conducted intensive studies to determine the cause of the degradation of reliability. As a result, the inventors have discovered that the degradation of reliability (BDV) is attributable to the presence of the dummy conductors. In more detail, the inventors have discovered that, when the dummy conductors are present in an outer layer portion where there are no inner electrodes, the inner electrodes positioned in overlapped relation to the dummy conductors are excessively pressed in a pressing step before firing due to the presence of the dummy conductors, and the distance between the inner electrodes adjacent to each other is locally shortened.